Device for measuring the pressure exerted on cutting tools



July 26,1949. E A T. HUGHES DEVICE F0 Filed July 51, 1946 EXERTED ON CUTTING TOOLS R MEASURING THE PRESSURE 2 Sheets-Sheet 1 July 26, 1949. HUGHES 2,477,457

- DEVICE FOR MEASURING THE PRESSURE v EXER'I'ED ON CUTTING TOOLS Filed July 31, 1946 2 Sheets-Sheet 2 Patented July 26, 1949 newer: FOR- MnAsUnINe r nn me sage EXERTED on CUT-TINGYTOGLS b t T Hashes, Wal s Application July 31, 1946, Serial no. sm-"49a i In Great Britain July gil, 1945 Section Public Law 699, a gust 3, 946

Patent expires July 30,19,65

7 claims. (01. m n -111 i) This invention 'relatestodevices formea'su'ring forces exerted in various directionson "cutting tools of machines such as lathes, planing machines andthe like. i In accordance with the invention the cutting toolis mounted in a tool holder which has a portionarranged as a ball joint or the like in arigid housing so that it may move in any direction in the housing. A portion of the seating forthe tool holder in the housing is formed by a static pressure transmitting device whichwill 'indicate the loada'pplied tothetool with practically no movement. In addition the tool holder is fitted with contacts say in line or at any tangent to the tool; each 1 cooperating with'a separate static pressure transmitting device to measure the force in any other direction. By this arrangement eaciili'orice is measured in the direction in which it is applied and with practically no movement.

Each of the static pressure transmitting devices may be connected by fluidpressure conduits-with pressure gauges suitably disposed. l a

One embodiment of the invention applied t a lathe-tool machinability testing machine is illustrated in the accompanying drawings in WhiQh Fig. -1 is. a longitudinalvertical axial section, Fig. 21s a side elevation. 3 isahorizontal axial section and Fig. 4 is a rear elevation partly in section on the line C-C of Fig. 3.

As shown in Figs. 1 and 2, the cutting tool 5, the forces on which are to be measured, is mounted in a tool holder 6 by set screws 5a, the holder presenting a partly spherical surface 6a and supported on a partly spherical seating 8 of a ring la, in a rigid housing I, this arrangement allowing for a small turning movement of the tool holder 6 in any direction. The ring la together with the channel ring 10 cooperate to provide an annular casing of a static pressure transmitting device indicated by the reference character I, such device being adapted to measure the load applied to the tool 5 with practically no movement. The ring la includes a flange ex tending into the channel of the ring Ic so that an annular chamber Id for pressure fluid is formed. The channel ring part I of the device I0 is held in position by a plate 9 bolted to the housing I by bolts 9a. A screw threaded collar ll] engaging the plate 9 and pressing against a washer Illa bearing on the ring lc of the pressure transmitting device I serves to pre-load and position the transmitting device I. A distance piece ll interposed between the housing 1 and the ring la of the transmitting device serves to determine the forward position of the ring la of the transmitting device. The device I measures the thrust of the tool 5 in the rearward direction, o

The upper side of the tool holder ii, as shown ihFigs. 1 and'Z-is providedwith a pressure transmittingdevice 2 mounted in a verticalv plane containing theaxis ofthe'tool 5 and s'etat 'a slight forward inclination. The device 2 com prisesa channel ring 2a with a downwardlyprojecting annular channel and a member icincluding an annular flange extending into the channel of the ring 211 to form a chamberfZd' for pressure fluid. The member 20 rests upon a. ball contact l3 engaging aninclined surlface 13a on the upper portion of the tool holder 6." channel ring 2a is mounted in an opening I21 in the upper part of the housing 'I andis carried by a member 12d bolted to a plug 12b threaded into the outer portion of the opening 12. Ascrew' threaded plug 14 projects from the housingi and has a ball contact bearing on the end of the tool holder remote from the surface Hat-serv ing to pro-load the transmitting device 2' and position the tbol holder 6.

to the tool by -the work;

The side of the tool holder 6 asshown in Figs.

3 and .4 isprovided with a pressure transmittingdevice 3 mounted in a horizontal plane containing the axis of the tool 5 and inclining forwardly. The device 3 comprises a channel ring 3a with a downwardly projecting channel and a member 30 including an annular flange extending into the channel of the ring 3a to form a chamber 3d. The member 30 carries a ball contact l6 bearing on an inclined surface I! on the side of the tool holder 6. The channel ring 3a is carried by a member I50, bolted to a plug I5b threaded into an opening [5 inside of the housing 7.

A screw threaded plug I8 in the housing I at the end of the tool holder remote from the surface I! and in the same horizontal plane as the transmitting device 3 is provided with a ball contact engaging the tool holder 6. The plug [8 serves to pre-load the transmitting device 3 and position the tool holder. This third transmitting device 3 serves to measure the longitudinal force applied to the tool by the work.

A fourth pressure transmitting device 4 is mounted between the base of the housing 1 and a surface IQ of the tool holder 6, said surface lying in a horizontal plane passing through the axis of the tool 5 as shown in Fig. 4. One part 40 of the pressure transmitting device 4 is a plunger extending into a chamber for pressure fluid in a base portion 4d, secured to the housing 1 by This second device 2 serves to measure the-tangential forceapplied screws as shown. The device 4 also includes a vertical bar 4a, the lower end of which rests upon 'a ball 20a carried by the plunger 40. The upper of the axis of the tool holder 6 from the transmitting device 4, as shown in Fig. 4, carries a ball contact abutting against a surface 22 in tool holder 6 at the plane of the surface IS. The plug 2| serves to preload the transmitting device 4 and position the tool holder 6. This fourth static pressure transmitting device serves to measure the torque applied to the tool by the work.

Pressure gauges lb, 2b, 3b and 4b. shown in Fig. 4, two of which are also shown by dot-anddash lines in Fig. 2, are provided for indicating the pressures applied in the various directions as transmitted by the devices I, 2, 3 and 4,-the fluid pressure chambers of which are respectively connected by means of conduits le, 2e, 3e and 4e 7 to the pressure gauges.

V Iclaim: v I

1.' A lathe tool machinability testing machine including a partly spherical tool holder mounted in partly spherical seatings in a rigid housing to allow a universal turning movement of the tool holder, a static pressure transmitting device forming part of the spherical seating at the rear of the tool holder and serving to measure the rearward thrust on the tool, a. static pressure transmitting device interposed between an abutment lying in the vertical axis of the tool holder and the housing, and static pressure transmitting devices operable by abutments one lying in a horizontal plane including the horizontal axis of the tool holder and serving to measure the longitudinal force on'the tool and the other abutment lying in a vertical plane intersecting the horizontal axis of the tool holder and serving to measure the torque on the tool.

2. In a. machine for measuring forces exerted between a cutting tool and a. piece of material being cut. thereby, a rigid housing for a tool holder, a tool holder mounted therein, a ball and socket joint between the tool holder and the housing, a static pressure transmitting device arranged to 4 transmit the backward thrust pressure on the tool having a. portion arranged as a part of the ball and socket joint, and a plurality of seatings in the tool holder, a plurality of static pressure transmitting devices cooperating with the respective seatings in the tool holder and with the housing for transmitting and measuring forces applied to g the tool in other directions.

- 3. A machine as defined by claim 2 including means. for preloading each pressure transmitting device.

4. In a testing machine for testing the machinability of materials, a rigid housing for a tool holder including a pair of spherical socket seatings, a tool holder having a spherical portion mounted between the socket seatings of the housing whereby universal turning movement of the tool'holder is permissible, and a Static pressure transmitting device including the spherical seating of the housing at the rear of the tool holder, said device serving to measure the rearward thrust on the tool.

5. A machine as defined by claim 4 mwhicn means is provided for preloading the pressure transmitting means. r

6. A machine as 1 defined by claim 5 in which the preloading means comprises a threaded sleeve acting upon the spherical seating at the rear of spherical portion of the tool holder, said seating at the rear of the tool holder being movable axially with respect to the housing.

, 7. A machine as defined by claim 4 characterized by including a static pressure transmitting device operable by an abutment on the tool holder and lying on a plane including the axis of the tool holder, and means for preloading said lastmentioned device.

. ALBERT T. HUGHES.

REFERENCES CITED The following references are of record in the file of this patent:

V UNITED STATES PATENTS Number 

